Autoclave

Abstract: An autoclave (1) and associated method for sterilising generally hollow articles, such as, dental drill handpieces (21), comprises means (17, 20) for passing a sterilising fluid, for example dry saturated steam, through a generally hollow article (21) with opening (22) at remote ends thereof, to sterilise the interior thereof.

Description: This invention relates to an autoclave for and an associated method of sterilising handpieces for dental drills having openings at remote ends thereof. Known autoclaves for sterilising handpieces for dental drills comprise a closed chamber through which a sterilising agent, such as ozone or a cleansing fluid, can be passed or circulated and in which one or more handpieces to be sterilized can be mounted. During sterilisation, the sterilising agent is supposed to sterilise all of the surfaces of the handpieces which have been exposed to contamination during use. However, because the pressure of the sterilising agent is generally the same at both open ends of the generally hollow handpieces, a comparatively small amount of sterilising agent is able to pass into and through the handpieces, such that the hollow interiors thereof are not sterilised properly. This may well result in contamination and/or infection of a patient upon whom an improperly sterilised handpiece is used subsequently. Such known types of autoclave are disclosed in DE-A-3239549, EP-A-0281870 and GB-A-2136911. Further particles of tissue and broken tooth can become clogged inside the hollow interiors of the handpieces, whereby use of known types of autoclave is not capable of dislodging such foreign matter, thus resulting in an undesirable build-up of such matter inside the handpieces, with consequential contamination and/or infection of patients upon whom the supposedly cleaned and sterilised handpieces are used. Generally, the prior art autoclaves can be described as comprising: a cylindrical body divided into a sterilising chamber and a sterilising agent chamber; and at least one adaptor which is arranged to receive sterilising agent from the chamber and which is arranged to receive thereon a generally hollow dental drill handpiece to be sterilised, at the first end opening thereof, whereby, in use, sterilising agent from the chamber can pass into, through and from the handpiece at the second end opening thereof. A corresponding prior art method can be described generally as comprising: providing a cylindrical body divided into a sterilising chamber and a sterilising agent chamber; mounting a dental drill handpiece to the adaptor, at a first end opening of the handpiece; and supplying sterilising agent from the agent chamber to the interior of the handpiece via the adaptor and its first end opening, to cause sterilising agent to pass through and from the handpiece at a second end opening of the handpiece, thereby sterilising the handpiece. It is an object of the present invention to provide an autoclave which overcomes or at least substantially reduces the serious disadvantages associated with known types of autoclave, such as those discussed above. It is another object of the invention to provide a method of sterilising generally open-ended, hollow articles, such as, handpieces for dental drills, which also overcomes or at least substantially reduces the disadvantages of known sterilising techniques. Accordingly, the autoclave of the invention is characterised from the prior art autoclaves, in that, firstly, a carrier is mounted on a sterilising agent generation chamber, with said at least one adaptor attached to the carrier in communication with the generation chamber and, secondly, the sterilising agent generation chamber is a dry saturated steam generation chamber, the pressure in the sterilising chamber being above atmospheric pressure. Preferably, the generation chamber is also capable of causing the so-generated dry saturated steam to pass through a dental drill handpiece received on the carrier at a pressure sufficient to dislodge foreign matter from the interior of the handpiece. The inventive method is characterised from the prior art methods, in that the first end opening of the dental drill handpiece is mounted to the adaptor which is attached to a carrier mounted on the sterilising agent generation chamber in communication therewith and the sterilising agent supplied to the interior of a handpiece from the generation chamber is dry saturated steam. Preferably, the dry saturated steam is supplied to the handpiece interior at a pressure sufficient to dislodge foreign matter therefrom. The adaptor may be modified so that the steam pressure is sufficient also to rotate the handpiece about its longitudinal axis during sterilisation. Such rotation may assist further in dislodging any foreign matter from the handpiece interior. The adaptor can be arranged to receive different sizes of handpiece and may be connected thereto by a push-fit, screw thread or other suitable means. When handpieces having their working heads driven by air motors, turbines or other rotating means, are to be sterilised then the adaptor of the carrier may be such that the pressurised steam can rotate the driving air motors, turbines, or other rotating means associated with the handpiece. Alternatively, the adaptor may be designed to rotate the handpiece about its normal air bearing in any suitable manner, for example, by being rotated itself such that the handpiece which is fixed thereto is also rotated. However, other suitable means may be provided for rotating the handpiece and/or adaptor. In order that the invention may be more fully understood, a preferred embodiment of autoclave in accordance therewith and for putting the inventive method into effect, will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is a cut-away, elevation in partial section of an autoclave for sterilising handpieces for dental drills; and Figure 2 is a plan view of the autoclave of Figure 1. Referring now to the drawings, an autoclave for sterilising dental equipment, in particular handpieces for dental drills, is shown generally at 1 and comprises a cylindrical body 2 divided into an upper, sterilising chamber 3 and a lower, steam-generation chamber 4 by means of an annular support 5. Respective lower and upper ends of cylindrical wall portions 6,7 of the body 2 engage sealingly with the annular support 5 by means of seals 8,8'. Similarly, the respective upper and lower ends of those wall portions 6,7 engage sealingly with top and base plates 10 and 11 by means of seals 9,9'. A lid 12 is sealed to the top plate 10 via an annular lip 13 and is located ir position by means of four fixing studs 14 situated at the top ends of respective clamping rods 15 which, in combination with retaining nuts 16 (only one shown), clamp the autoclave assembly together. Mounted on the support 5 in the upper, sterilising chamber 3 is a circular carrier 17 resting upon another seal 18 located in an annular groove in the support 5. A plurality of adaptors 20 (only one shown) are arranged on the upper surface of the carrier 17 for receiving thereon respective handpieces 21 for dental drills (not shown). The handpieces 21 are generally tubular and hollow and each have an open end, in this case, the lower end, and the opposed end provided with openings dependent upon their particular construction. An axial bore 22 in each adaptor 20 lies in register with a corresponding aperture 22', or tube as an alternative, passing through the carrier 17, such that the hollow interior of the handpiece 21 is in communication with the lower, steam-generation chamber 4, via the large central aperture of the annular support 5. The other, upper end of the handpiece 21 is in communication with the interior of the upper, sterilising chamber, via the openings in that end, which, in turn, communicates with the atmosphere via a hole 23 and an exhaust port 24 in the support 5. The hole 23 or the exhaust port 24 may be provided with a bleed valve, as will be mentioned hereinbelow. A heating element 25 is provided in the lower chamber 4 for heating water 26 contained therein, with associated electric terminals 27 located on the underside of the base plate 11. Also, the carrier 17 has a handle 28 for manoeuvering the carrier, and any handpieces 21 mounted thereon, in and out of the sterilising chamber 3. The lid 12 is removable, whilst the carrier 17 is dimensioned so that it can be passed through the circular central aperture 29 in the top plate 10, with the lid removed. Further, the handpieces 21 are, in use with a dental drill, air driven and the adaptors are such that, when a handpiece is mounted upon one, as shown in Figure 1, and steam is generated in the lower chamber 4, steam passing through the hollow interior of the handpiece 21 is at a sufficient pressure to rotate the air motor or turbine of the handpiece or the handpiece itself during sterilisation thereof. Such rotation assists in dislodging any foreign matter, such as, particles of tissue and/or broken tooth, from the interior of the handpiece, which matter might not otherwise be dislodged by conventional sterilising techniques. A pressure relief valve 30 for the lower chamber 4 is also provided in association with the support 5, for emergency purposes. In use of the inventive autoclave 1 described above in relation to the drawings, the carrier 17 bearing one or more handpieces 21 mounted on associated adaptors 20, is placed in the upper chamber 3, seated upon the seal 18 of the support, to provide a steam-tight seal between the upper and lower chambers 3,4. The lid is then secured in position using the fixing studs 14. Then, the lower chamber 4 is filled to a given level with water 26 and the heating element 25 is switched on. As the water 26 boils, the pressure in the lower chamber 4 increases to provide dry saturated steam at a temperature of, say, 134°C. Because the pressure of the steam in the lower chamber 4 is greater than the pressure in the upper chamber 3, the dry saturated steam passes through each aperture or tube 22' in the carrier 17 and each corresponding in-register bore 22 of each adaptor 20, so that the steam eventually passes through the hollow interior of each handpiece 21 and into the upper chamber 3, via the openings in the upper end of each handpiece, where it sterilises the outer surfaces of the handpiece. Passage of the dry saturated steam through the hollow interior of each handpiece 21 not only sterilises the interior of each handpiece but also assists in dislodging any foreign matter which may have built-up inside the handpieces. Further, the pressure of the steam, and hence its rate of flow through the interiors of the handpieces 21, is sufficient to rotate the handpieces upon their respective adaptors 20 or the air motors or turbines for driving the working heads of the handpieces 21. The steam pressure generated within the upper chamber 3 during normal use of the autoclave 1 will be about two atmospheres, although other steam pressures are acceptable, depending upon particular operating conditions. Similarly, the suggested dry saturated steam temperature of 134°C can also be varied, again depending upon operating conditions. A predetermined sterilising cycle time for the autoclave 1 can be provided in dependence upon a leakage setting of a bleed valve (not shown) associated with the hole 23 and/or steam exhaust port 24, a given amount of water contained in the lower chamber 4 and a given temperature and pressure of the dry saturated steam. The adaptors 20 can be arranged to receive different sizes of handpiece 21 and may be connectable thereto by a push-fit, screw thread or any other suitable means.

Claims: An autoclave (1) for sterilising a generally hollow dental drill handpiece (21) having a first end opening and a second end opening remote from the first end opening, the autoclave (1) comprising: a cylindrical body (2) comprising a sterilising chamber (3); and at least one adaptor (20) which is arranged to receive sterilising agent and which is arranged to receive thereon a generally hollow dental drill handpiece (21) to be sterilised, at the first end opening thereof, whereby, in use, sterilising agent can pass into, through and from the handpiece (21) at the second end opening thereof, characterised in that: the cylindrical body (2) further comprises a sterilising agent generation chamber (4); and a carrier (17) is mounted on the sterilising agent generation chamber (4) with said at least one adaptor (20) attached to the carrier (17) in fluid communication with the sterilising agent generation chamber (4); and the sterilising agent generation chamber (4) is a dry saturated steam generation chamber; and the sterilising chamber is at a pressure above atmospheric pressure. An autoclave (1) according to claim 1, wherein the dry saturated steam generation chamber (4) is capable of causing the so-generated dry saturated steam to pass through a handpiece (21) received on the carrier (17) at a pressure sufficient to dislodge foreign matter from the interior of the handpiece (21). An autoclave (1) according to claim 1 or 2, wherein the adaptor (20) is arranged so that, in use, the dry saturated steam pressure is sufficient also to rotate the handpiece (21) about its longitudinal axis during sterilisation thereof. An autoclave (1) according to claim 1, 2 or 3, wherein the adaptor (20) is arranged to receive different sizes of handpiece (21). An autoclave (1) according to any preceding claim, wherein the adaptor (20) is connectable to a handpiece (21) by a push-fit, screw thread or other suitable means. An autoclave (1) according to any preceding claim, wherein the adaptor (20) is arranged such that pressurised, dry saturated steam can rotate any air motor or turbine associated with the handpiece (21). An autoclave (1) according to any preceding claim, wherein the adaptor (20) is arranged to rotate a handpiece (21) by being rotated itself, such that, in use, the handpiece (21) fixed thereto is also rotated. A method of sterilising a generally hollow dental drill handpiece (21) having a first end opening and a second end opening remote from the first end opening, which method comprises: providing a cylindrical body (2) comprising a sterilising chamber (3); and mounting a dental drill handpiece (21) at its first end opening to an adaptor (20); and supplying sterilising agent to the interior of the handpiece (21) via the adaptor (20) and the first end opening of the handpiece (21), to cause sterilising agent to pass through and from the handpiece (21) at the second end opening thereof thereby sterilising the handpiece (21), characterised in that: the first end opening of the dental drill handpiece (21) is mounted to the adaptor (20) which is attached to a carrier (17) mounted on a sterilising agent generation chamber (4) in communication therewith; and the sterilising agent supplied to the interior of the handpiece (21) from the generation chamber (4) is dry saturated steam; and the pressure in the sterilising chamber is above atmospheric pressure. A method according to claim 8, wherein the dry saturated steam is supplied to the interior of the handpiece (21) at a pressure sufficient to dislodge foreign matter therefrom. A method according to claim 8 or 9, wherein the adaptor (20) is arranged so that the pressure of the dry saturated steam is sufficient also to rotate the handpiece (21) about its longitudinal axis during rotation thereof. A method according to claim 8, 9 or 10, wherein the adaptor (20) is connected to the handpiece (21) by a push-fit, screw thread or other suitable means. A method according to any of claims 8 to 11, wherein the adaptor (20) is arranged so that pressurised dry saturated steam rotates any air motor or turbine associated with the handpiece (21). A method according to any of claims 8 to 12, wherein the adaptor (20) rotates the handpiece (21) by being rotated itself.

Inventors: JENNINGS STANLEY CLIFFORD, JENNINGS, STANLEY CLIFFORD
Applicants: JENNINGS STANLEY CLIFFORD, JENNINGS, STANLEY CLIFFORD
Application year: 1994
Main classification: A61L2
IPC codes: A61L2, A61C19